John N. Bahcall

John Norris Bahcall (December 30, 1934 – August 17, 2005) was an American astrophysicist and the Richard Black Professor for Astrophysics at the Institute for Advanced Study. He was known for a wide range of contributions to solar, galactic and extragalactic astrophysics, including the solar neutrino problem, the development of the Hubble Space Telescope, and his leadership and development of the Institute for Advanced Study in Princeton.<ref name="Tremaine">Template:Cite book</ref><ref name="Haxton">Template:Cite journal</ref>

Early life and education

Bahcall was born into a Jewish family in Shreveport, Louisiana on December 30, 1934,<ref name="Overbye">Template:Cite news</ref> and would later describe an early aspiration to become a Reform rabbi.<ref name="Avrahami">Template:Cite news</ref> He did not take science classes at high school.<ref name="Tremaine"/> In high school he was a state tennis champion<ref name="Haxton"/> and a national debate champion (1952).<ref name="Tremaine"/>

Bahcall began his university studies at Louisiana State University as a philosophy student on a tennis scholarship, where he considered pursuing the rabbinate. At the end of his freshman year, he transferred to the University of California, Berkeley, still studying philosophy.<ref name="Tremaine" /> He took his first physics class to fulfill a graduation science requirement, later saying:<ref name="Wilson" />

Bahcall switched majors to physics,<ref name="Tremaine" /> and graduated with an AB in Physics from Berkeley in 1956. He obtained his MS in physics in 1957 from the University of Chicago and his PhD in physics from Harvard University in 1961.<ref name="Tremaine" /><ref name="Haxton" />

He spent a year as a research fellow in physics with Emil Konopinski at Indiana University. From 1962 to 1970, he worked with a group led by William Fowler at the Kellogg Laboratory of the California Institute of Technology,<ref name="Haxton" /> first as a research fellow and later as an assistant and associate professor.<ref name="AIP" />

Academic career

Bahcall joined the Institute for Advanced Study in Princeton, New Jersey in 1968<ref name="Ostriker">Template:Cite journal</ref><ref name="Tremaine" /> becoming a professor of natural sciences in 1971 and the Richard Black Professor of Natural Sciences in 1997.<ref name="AIP">Template:Cite web</ref>

Bahcall became a member of the National Academy of Sciences in 1976.<ref>Template:Cite web</ref>

He was president of the American Astronomical Society from 1990 to 1992,<ref name="Wilson">Template:Cite news</ref> and was president-elect of the American Physical Society at the date of his death.<ref name="APS2005">Template:Cite journal</ref>

Research

Bahcall published over six hundred scientific papers<ref name="Ostriker"/> and wrote or edited nine books on astrophysics.<ref name="Haxton"/>

He is most notable for his work in establishing the standard solar model. He spent much of his life pursuing the solar neutrino problem with physical chemist Raymond Davis, Jr. Together, Davis and Bahcall collaborated on the Homestake Experiment. To test Bahcall's theoretical predictions, Davis created an underground detector for neutrinos in a South Dakota gold mine, essentially a large tank filled with cleaning fluid. The flux of neutrinos found by the detector was one-third the amount theoretically predicted by Bahcall, a discrepancy that took over thirty years to resolve.<ref name="Haxton"/><ref name="Jelley">Template:Cite journal</ref><ref name="Martin">Template:Cite book</ref> Bahcall's ongoing research in this area resulted in publication of his book Neutrino Astrophysics (1989), considered a standard reference on solar neutrinos.<ref name="Tremaine"/><ref>Template:Cite book</ref>

The 2002 Nobel Prize in physics was awarded to Davis and Masatoshi Koshiba for their pioneering work in observing the neutrinos predicted from Bahcall's solar model, thereby vindicating Bahcall's prediction.<ref name="Nobel">Template:Cite web</ref><ref name="Holley">Template:Cite news</ref>

In addition to his work on solar neutrinos, Bahcall collaborated with Eli Waxman on the Waxman-Bahcall bound for high energy neutrinos. This bound sets a limit on high energy neutrino flux based on the observed flux of high energy cosmic rays. It was not possible to verify this prediction until after his death, with the construction of neutrino telescopes capable of detecting very high energy neutrinos, such as the IceCube Neutrino Observatory.<ref name="Haxton"/><ref name="Tremaine"/><ref name="Waxman">Template:Cite journal</ref>

Another contribution of Bahcall to astrophysics was the development and implementation of the Hubble Space Telescope, in collaboration with Lyman Spitzer, Jr., from the 1970s through to the period after the telescope was launched in 1990.<ref name="Haxton"/><ref name="Tremaine"/> In 1992, Bahcall received the NASA Distinguished Service Medal for this work.<ref name="NASA2006"/><ref name="Kaufman">Template:Cite news</ref> He reintroduced the traditional method of star counts, as a quantitative tool for assessing galactic structure.<ref name="Pinsonneault">Template:Cite journal</ref>

The standard model of a galaxy, with a massive black hole surrounded by stars, is known as the Bahcall-Wolf model. The Bahcall-Soneira model was for many years the standard model for the structure of the Milky Way. He also contributed to accurate astrophysical models of stellar interiors.<ref name="Haxton"/><ref name="Tremaine"/>

Personal life and death

Bahcall married Princeton University astrophysics professor Neta Bahcall, whom he met as a graduate student at the Weizmann Institute in the 1960s. They had a daughter and two sons (including Safi Bahcall).<ref name="Haxton" /><ref name="Ostriker" />

He died in New York on 17 August 2005, from a rare blood disorder.<ref name="Holley" /><ref name="Overbye" />

Honors

• 2006, Exceptional Scientific Achievement Medal (posthumous), NASA<ref name="NASA2006">Template:Cite news</ref>
• 2004, Academy of Achievement, Golden Plate Award<ref>Template:Cite web</ref>
• 2004, Comstock Prize in Physics from the National Academy of Sciences<ref name=Comstock>Template:Cite web</ref>
• 2003, Gold Medal of the Royal Astronomical Society<ref>Template:Cite journal</ref>
• 2003, Benjamin Franklin Medal (with Raymond Davis, Jr. and Masatoshi Koshiba)<ref name="Gaisser">Template:Cite journal</ref>
• 2003, Dan David Prize<ref name="DDP">Template:Cite web</ref>
• 2003, Fermi Award (with Raymond Davis, Jr)<ref>Template:Cite web</ref>
• 2001, Member of the American Philosophical Society<ref>Template:Cite web</ref>
• 1999, Henry Norris Russell Lectureship<ref>Template:Cite web</ref>
• 1998, National Medal of Science<ref>Template:Cite web</ref>
• 1998, Hans Bethe Prize<ref>Template:Cite web</ref>
• 1994, Heineman Prize<ref>Template:Citation</ref>
• 1992, NASA Distinguished Public Service Medal, NASA<ref name="NASA2006"/>
• 1976, Fellow of the American Academy of Arts and Sciences<ref name=AAAS>Template:Cite web</ref>
• 1970, Helen B. Warner Prize<ref>Template:Citation</ref>

External links

• Solar neutrinos: history
• Institute for Advanced Study:
  • Homepage
  • Biography
  • Press release following his death
• PBS Nova: The Ghost Particle
• Letter from his family after his death